Homeland security is tricky work. The bad guys can appear to be innocent and apple-cheeked. The innocent can look like assassins. For example: On this date in 1949 a swarthy, muscular man named Arthur Schabbe left his apartment in northwest Washington, D.C., and took a street car to a point about six blocks north of the White House. He entered a butcher shop and caught the eye of an attendant, Jimmy Perkins.

In a low voice, Schabbe said, “Do you have it ready?”

“It’s in the back.”

“I’ll come with you.”

The two men stepped through a swinging door and into a meat locker. Perkins opened a low-lying cupboard. He removed a small oval package wrapped in brown paper.

“Do you want to examine it?”

Schabbe said, “No. I trust you. Here’s your money.”

He left the butcher shop and turned south toward Pennsylvania Avenue. The time was 11:30 a.m. Somewhere a radio was playing “Nature Boy,” made famous a year earlier by Nat King Cole. Schabbe would recall all these details many years later, when I was trapped beside him on a bus ride between Toledo and Pittsburgh.

In the Oval Office, President Harry S. Truman was signing a bill that would fund a quail preserve in Oklahoma. He smiled, recalling the satisfaction he had felt the night before, during a poker game in which his full house had beaten a flush held by Treasury Secretary Fred Vinson, whose face resembled that of a bloodhound.

Arthur Schabbe arrived at the White House a few minutes before noon. He took a position against the steel fence that rimmed the south lawn. Tourists and pedestrians soon joined Schabbe. They awaited the sight of President Truman, who often took a brisk pre-lunch walk on the White House grounds.

A few moments later, Truman appeared. Schabbe felt his heart rate jump. He removed the oval package from his coat and began to unwrap it. As luck would have it, the president and his small entourage were heading toward Schabbe.

When Truman was only 50 yards away, Schabbe took the object from its wrappings and lifted it upward toward his face. At that moment, two Secret Service agents grabbed Schabbe’s arms, rendering him powerless.

Five minutes later Schabbe found himself in a small room a block west of the White House.

“Who are you?”

Schabbe told them.

“What is the meaning of this object you were pointing at the president?”

“It is a horsemeat sandwich. I had it made special for me by a butcher on 16th Street. I wanted to be the first person in my family ever to eat horsemeat in front of a U.S. president.”

Three hours later Schabbe was released. He never got to eat his sandwich, and never again tried. The President was not told about the incident.

Now you know why security work is so tough. You look for a John Hinckley, and you come up with a horsemeat sandwich.